1. Field of the Invention
This invention relates generally to smoking articles such as cigarettes, cigars and the like and the wrapper for the tobacco column thereof, and more particularly to an improved wrapper for such smoking articles for use either by itself or as an inner wrapper in combination with a conventional outer wrapper which significantly reduces the amount of visible sidestream smoke that normally emanates from a smoking article during static burning.
2. Prior Art
One of the common problems associated with smoking articles such as cigarettes or cigars is the amount of sidestream smoke that is given off during static burning, for example when the smoking article is idling and not being drawn upon by the smoker or is simply resting in an ashtray while burning. Visible sidestream smoke that is given off by a smoking article such as a cigarette during static burning is comprised mainly of particulate matter and the smoke is irritating and objectionable to nonsmokers in the vicinity of the idling cigarette. Various mechanisms have been incorporated into smoking articles to reduce visible sidestream smoke but none to date has been commercially successful in cigarettes. Probably the most effective means of reducing visible sidestream smoke is disclosed in U.S. Pat. No. 3,744,496 in which a smoking article such as a cigarette is designed to include an inner wrapper around the tobacco charge containing finely pulverized carbon particles in combination with a conventional outer wrapper of cigarette paper. However, due to the carbon employed in such wrappers they have not found widespread use in cigarettes primarily because of the objectionable dark color imparted to the wrapper from the carbon. Their success has mostly been in the cigar field where the darker wrap is less noticeable and therefore not objectionable. In any case, carbon filled wrappers have proved to be very successful in reducing sidestream smoke emanating from a smoking article during static burning.
Conventional cigarette paper normally contains a filler of calcium carbonate to improve the appearance and properties of the paper. In addition, various burning chemicals may also be added to the paper furnish to improve the burn rate and ash characteristics of cigarettes made therefrom. Cigarette papers containing such materials are disclosed in U.S. Pat. Nos. 2,580,611, 2,652,834, and 2,733,720. None of the additives used in such conventional cigarette papers have a significant effect upon reduction of undesirable constituents in the cigarette smoke or effectively reduce visible sidestream smoke. It is also known to coat cigarette papers with a thin layer of metal such as aluminum or aluminum-base alloys to increase the burning temperature of the smoking article as disclosed in U.S. Pat. No. 3,586,005. Such metal coated cigarette papers have little effect upon reducing visible sidestream smoke. U.S. Pat. No. 2,673,799 discloses a method for improving the ashing properties of cigarette paper when burned as a wrapper on a cigarette by incorporating small amounts of magnesium carbonate in cigarette paper. The amount of magnesium carbonate employed in such papers preferably falls within the range of approximately 0.5 to 2.0% based on the weight of the filler. While papers produced in this manner do have improved ashing properties, they do not reduce visible sidestream smoke.